Chlorination process for treating ores



Dec- 14, 1954 A. D. HADSEL cHLoRINATIoN PRocEss FOR TREATING oREs Filed May 15, 1950 IN VEN TOR. /Vah D. Hadse/ TTNE Y United States Patent .52597,034 'CHEORIISIATIONTRO'CESSTQR TREATING 'kEs Aryan D. inadselynubum, Calif.'

vApplication May 15, -v1950Serial 4No. `162081 '4i'ciims. Clins-112),

Thepresent invention relateslo improvementsin a .chlorination .process vfor.ltreat'ir1 g. or.e s, .andhas .particular reference. to .the treatment `of.concentrates of .complex sulfide ores, although :various ,pr incip`les of the :invention A4may' be used .in lthe treatmentiof other oreconcentrates .for of ,p lverized ores Which.,fdo 5not-need` concentration.

'.Ores of .thecharacterfunder considerationmay be crushed and comminutedin a conventionalfmanner and vsubjected to allotationprocess'toseparate the metal'bearing concentrates from wastematerial. Other-.ores,..again,

.such .as lirnestonegmagnesite and Aserpentine may be .merelypulverized in .preparation for .my process yWhile ythese operations usually takeplace atthe mine, -it .has been .custonaryf to. ship the concentrates .togthe smelter for further .treatment .which .involves 'considerableexpense andusuallymakes'the operationoffsorcalled marginal mines unprotable except. at times where unusu- .ally .high .prices prevail. furthermore in .smeltingproc- `e'ss'es commonly .employed @thev sulfur presentin fthe: suldes .is .usually a Waste vproduct vvWhichfuther. .reduces/the value of'theoncentrates.

' In the present invention it'is proposed to .provide a chlorination Vprocess forthe treatment ofthe yconcentrates which. can 'be carriediout ibyythe.. use. of .comparatively 'simple vand..inexpensive .apparatus so as to befgdapted `for instll'ationat `the mine and 'to.eliminatethey shipping of .the concentrates'.tozilistant.srneltersl It yis' further proposed to .provide a chlorination .process .in whichthe sul-fur present zin .the 'concentrates is madeto `rise to the surfaceof. the body under treatment andis 'recovered jas an independent marketable Afpro'duct.

It vis further proposed Itoprovide aehloririation .process .which all thev suldespresjentare,turned into 4chlorides "and in `which` 'the'nalpro'ductfis any'clearjliquid'gholding .the metal chlorides in solution, and `fro1 n'Whieh. 'the metals maybe recovered bya relatively. simplegiproessgofpro- ,gressive .precipitation which .may falso; -be :readily carried out 'at the mine.

.-A typical sample of concentrates,v in .the treatment of 'which 'my' procesfs 'was developed, lmay jcon't'ain .approxivrnately the folloivingfingredients iinthe .proportions set 'foi-th:

"One Lof fthe outstanding :features of my 'chlorination process is Itemperature control. I have found -tha'tfor rn'y purposes the-chlorination Eprocess*should 4' becarrie'c'l out -a'tfre'l'a'tively1ow temperatures, prefera'bly'vvithin'the range of from C. -to 60 C., and lthat `even Within lthis 4range the lower temperatures are most effective.

Now, itis Well known jthat lthereactions-in a chlorinaftionp'ro'cess create-heat scient tov 'normally raise the temperature vof a body "under treatmentV considerably 'above the range of temperatures yindicated and also 1'greatly above the melting point -of fsulfur and even` above the melting points of someof themetals present, which again leads `to various reactions unfavorable to the process.

Ipjropose, therefore, toconduct theichlorintion process 'inth'e presence of, a coo1in'g;niedium, .andf'mo're .particuli'ly in"'t`11e presence .of 'an ample .body Of 'W'teL which 'i ce :kps '1t-heltemperaturedown-at .lefast to ;1( 0 .G, and vin View oftheaetthat the principal =featureof .m.y process, Lre'fer to f theplatte s as ubmergedfchlorination process. i Inordertorefectfa thorough mixing of. theconentrates and .the Water, I preferablylpremix .these 'cn- .stituentsjjn gaspecial pren-mixer orconditionerfnder ditions whieh Aallov'v fthe feed of Hconcentrates A:and tobefclosely-adjusted. f L .It-is fur-therproposed in the.presentf-inventionftofr i enhance v the .f cooling eiectfby continuously bypas'sing .a l.portion of thematerial under.treatmentjthrough. athiekener. containing la large body of .Water and .prefe i equipped :vi/ith. cooling coils, ,the thickener t t'li,v time servinggt'ofseparate-pregnant soltion frein.'solids',.l to discharge 'the-solution a's the'. finishedproductofjthe;` h lo- Krination process, and. vtoretu'rn. the .solidsfcarriedbypa 'co'l stream vof vwlaterlto'the chlorination. tank.

My A.process `is .preferably carriedgo'n vas 'afcoiit'inuous .process '.With..aco i 1"tinuous .'feed flpre-lii T carried concentrates, "a 'cont'inus B'ypa's's'ing ugh'fthc thickener, `and continuous discharge oftpregn nt. olutin. vSince thejprocesslis carried out at. 'alow v temperature the sulfur liberatedinthe chlorinatinp'rocess risesfftb the top voffthe mass under .treatment in .the forrn 'of'.a frothY WhichoWs over .intoa latinder and is sbjectedjto Vfurther treatmentl for separain'gp're sulfur from 'remaining L sulfides ,ianlf-to. return the-.1atter-into "thefehloriiiatin .process, this ,separating 'p'roees's bein'g preferably condUctedbatCh-Wise.

invention. I wish to have .it understood Vthat various changes and modiieations, maybe 'rnade 'in .the scope ,o'f vthe claims attached h'eieto 'Withot'd ar-tig from 'the spirit ing tank orfemulsiferz, a'thicker 3, afilter 4,ap're'gnat solution vstoragetank, asulfur separator. 6, a solvent 'agitator 7, fa ysulfur"p'r'ecipita'ti'on 'tank-f8, anda sulfur "filter 9. i

In .the first step j of the proe'ss' the concentrates, 'if A`d '1"`y, are lf'Cd fro'ina hopper 110 over a eiiveyorlljand nt'olth'e conditioner 1. 'At 'the same tirnewterfis fe'd into "the conditionerthrough the pipe '12, the Waterfbeingmete'red and 'being 4s upplie'd n sutlicint 'amount to fplro'vide yan easy o'win'g 'pulp-'intheconditionercornprising about 10% solids and '90% liq d `I f the'concentrates are alr'e "in ,pulp form, as .they 'might be.; coming "directly from the thickener 'of aottion`plat,'they might be `fed byjniear's vof a 'd iaphra'gmpump At any rate,v the niate'rialied should be undercontrolfas to quantity, Byfweight.

central shaftv 1"`6fha v i'1i` Vp "elle'r blades at its lower end to lset upfeircu'lation down hr.' the guide. The p'rinc pa f to thoroughly inix 'thef 'rne`t`e `red Water and 'the Wigh'ed ,`concentrte's,' to maintain afuniform 'pulp jdensityand to hold the solids in suspension 'until thefpulp is delivered "to the 'chlorinator 2.

A'conduit 17 connects 'theoiditioner 'v vith 'thehlofrfinator and lmay beprofvidedwithl a valve 18. The clatter rnight possible be ornt'tedif theconditioner 'and eh'lr'inator are disposed at ,theproper relative.elevatio'r`1s,` siilee va slightva'riation'n the'level of-"thecharge ihitheonditioner would not seriously affect the operation and a slight rise in the level would merely result in a corresponding increase in the velocity of the discharge, thus automatically adjusting itself.

The chlorinator 2 comprises in its principal features a rubber-lined tank 19, preferably cylindrical in form, equipped with a central draft tube 20 and a series of vertical vanes 21 connecting the tube and the tank to counteract centrifugal action. rl`he tank is closed on top and provided with a vent tube 22 having a cupshaped upper end, with a rubber ball 23 lying in the cup to yield to inside pressure. The draft tube stops short of the upper and lower ends of the tank, as shown.

A central shaft 24 is mounted in the tank and carries an impeller 25 at its lower end and below the draft tube. The impeller comprises a disc 26 having upper and lower impeller blades 27 and 28 mounted thereon. A conical intake 29 immediately below the impeller is connected to the chlorine tank 30, through a conduit 31 having a ow meter 32 therein. The lower corner of the tank is cut off by a frusto-conical barrier 32', and a similar barrier 33 is provided near the upper end at the elevation of the launder 34 surrounding the upper end of the tank and communicating therewith through openings 3S.

In operation, the upper blades of the impeller cause general circulation of the pulp which is drawn downwardly in the draft tube and rises outside the tube. The chlorine gas, which may be used approximately in the proportion of 1500 lbs. to a ton of concentrates, entering from the bottom, is thrown sidewise by the lower blades of the propeller and is thoroughly mixed into the agitated mass and partakes of the circulation. The chlorine reacts with the suldes to drive off the sulfur and to form chlorides, the specific reactions being substantially as follows:

Gold 2Au-l-3Cl2 2AuCl3 Silver Ag2S-i-Cl2 ZAgCI-t-S Copper CuS-i-Clz CuClz-l-S Lead PbS-l-Clz PbClz-l-S Zinc ZnS-l-Clz ZnClz-i-S Iron 2FeS-i-3Cl2 FeCla-l-S There may be variations in the metallic chlorides. Copper, for instance, may turn into CuCl, and iron into FeCla.

In the circulation process the level of the pulp in the draft tube 20 sinks below the level of the pulp outside the tube so that the pulp cascades down over the upper edge of the tube to form eddies which cause the free sulfur to liberate itself from the pulp and to rise to the top in the form of a froth which is forced outwardly by a conical disc impeller 36 for discharge into the launder 34.

ln view of the fact that the pulp is largely water, the

temperature in the chlorinator always remains cool and cannot rise beyond the boiling point of water. Cornparatively little pressure develops in the tank, but if there is any excess pressure it may be vented through the tube 22 and the ball valve 23.

But is is desirable that the temperature in the chlorinator be kept considerably below the boiling point of water. As a matter of fact, it should be kept fairly close to outside air temperature. To bring about an additional cooling effect I provide the thickener 3 which serves at the same time as an outlet for the pregnant solution containing the metal chlorides in solution. The thickener is of conventional form and a portion of the pulp in the chlorinator is continuously by-passed through the same. It is equipped with cooling coils 37 and the pulp is made to enter through a pipe 38 connected to the chlorinator intermediate its height and equipped with a valve 39.

Clear or pregnant solution containing the metal chlorides is spilled over the upper edge of the thickener into the launder 40, while the solids are worked toward the bottom and discharged through the bottom outlet 41, from where they are returned to the bottom inlet 29 of the chlorinator and are forced back into circulation by the lower vanes of the impeller 25. A valve 43 controls the pipe 42, and a small outlet 44 may be provided to d raw off a fractional portion of thickener under-flow to prevent the system from becoming clogged with in solubles.

The pregnant solution passes from the launder 40 through the filter 4, which may be of any suitable type adapted for clarifying the solution. The filter shown is a vacuum filter, vacuum being produced by the pump 46 in the pipe 47, which latter discharges the pregnant solution to the storage tank 5. This solution constitutes the final product of my chlorination process, and the metals and compounds contained therein may be readily recovered by progressive steps of selective precipitation which form no part of the present invention.

My invention was particularly developed in connection with the treatment of sulde ores and one of the principal objects of my process is to liberate the sulfur present and to turn the sulfur into a marketable product. It should be observed, however, that my submerged chlorination process, as hereinabove described, is adapted for treatment of any metal bearing ore concentrates or pulverized ores. If no sulfur is present, the steps relating particularly to the recovery of sulfur will, of course, be omitted.

As stated before, the sulfur liberated in the chlorination process in the form of a froth is thrown out by the impeller 36 into the launder 34 and from there it is advanced to the sulfur separator 6 for further treatment. While the submerged chlorination process hereinabove described is a continuous process, the sulfur treatment is preferably carried on in a batch process, and in order to tie up the latter process with the chlorination process so as to avoid interruption, I arrange the sulfur treating apparatus in duplicates or multiples, with the discharge conduit 48 arranged so that its discharge end may be shifted from one unit to the other. Only one of the units is shown and described in the present application.

Tests made in the operation of my invention developed that under certain conditions there was a tendency for fine sulde particles to collect with the sulfur in the froth and that a small amount of compressed air in a conical receptacle made a satisfactory separation of sulfur from the unfinished suldes, leaving the sulfur in satisfactory condition for most sulfur solvents. Any other means of separating the froth from the suldes would be satisfactory.

Thus, I provide in the first step of removing the sulfides the conical receptacle 6 into which the sulfur froth from the chlorinator is discharged. This receptacle has a bottom outlet 49 discharging into the pipe 50 controlled by a valve 51, the latter pipe leading back to the bottom of the chlorinator and having a compressed air inlet 52 at its free end for driving material descending from the conical receptacle 6 toward the chlorinator. Additional compressed air inlets are arranged near the bottom of the conical receptacle as at 53.

`Under the influence of the compressed air the sulfur froth is raised to the top of the receptacle and the remaining suldes sink toward the bottom for discharge into the pipe 50, by means of which they are returned into the chlorination circuit by the lower blades on the impeller 25.

The sulfur froth is skimmed from the top by a suitable continuous scraper 54 which delivers the froth upon an inclined trough 55 for delivery into the solvent agitator 7.

The agitator may be of any suitable type and its function is to dissolve the sulfur. Any suitable solvent may be used for this purpose but I found that caustic soda was most economical under normal temperature conditions and left the material in good condition for precipitation as atomic sulfur in the form of an extremely line powder.

The solvent agitator discharges, through a pipe 56, controlled by a valve 57, into the sulfur precipitation tank 8, where a small amount of a precipitatingv agent, such as an aliphatic alcohol known in the market as B-23, is added, and where the sulfur settles out. From here the sulfur flows, through a valve-controlled pipe S3, into the filter 9 of conventional construction from which the sulfur may be removed in wheelbarrows, indicated at 59, while the solvent discharges into a pipe 60 from where it may be pumped, by the pump 61, to waste or to the precipitation tank 8 or to the solvent agitator 7, depending upon the condition of the solvent.

While in my chlorinator I use an agitator exerting downward draft on the draft tube, any other suitable agitating means may be used, such as hydraulic agitation as used in the Pachuca tank in which the circulation is reversed and the material is forced upward in the draft tube. But it is essential to produce eddies for froth accumulation and means for removing the froth as it accumulates.

While in the flow sheet the chlorine tank is shown as being arranged below the chlorinator, for convenience of illustration, in actual practice it should be mounted at an elevation higher than the chlorinator to prevent tlow of the pulp toward the chlorine tank by gravity.

It should be noted that in this process the sulfur is taken out of the circuit as soon as it is liberated. This is important since otherwise the sulfur would eventually go into solution, as sulfuric acid and possibly some sulfur chloride, in which case the solutions would become too acidtfor satisfactory precipitation.

I claim:

1. A method of treating sulfide ore concentrates or the like which comprises the steps of mixing the concentrates with water to form an easy owing pulp of substantially uniform density, agitating the pulp in a container in a circulatory path, introducing chlorine into the path whereby sulfur is liberated, breaking the ilow of the pulp at a point along the surface thereof to produce eddies or whirlpools adapted for transforming the sulfur into froth and for continuously collecting said froth thereinto, and continuously withdrawing sulfur froth from said eddies or whirlpools.

2. A method of treating sullide ore concentratesv or the like which comprises the steps of mixing the concentrates with water to form an easy owing pulp of substantially uniform density, agitating the pulp in a container in a circulatory path including upstream and downstream courses extending through the height of the body, introducing chlorine into the path whereby sulfur is liberated, breaking the flow of the pulp at the point of the discharge from the upstream course into the downstream course in the top region of the body to produce eddies or whirlpools at said point for transforming the sulfur into froth for continuously collecting said froth thereinto, and continuously withdrawing sulfur froth from said eddies or whirlpools.

3. A method of treating sulde ore concentrates or the like which comprises the steps of, mixing the concentrates with water to form an easy flowing pulp of substantially uniform density, agitating the pulp in a container in a circulatory path including a central downstream course, and a surrounding cylindrical upstream course discharging into the downstream course in the top region of the body of the pulp, introducing chlorine into the path whereby sulfur is liberated, breaking the flow of the pulp at the point of discharge to produce eddies or whirlpools at said point for transforming the sulfur into froth and for continuously collecting said froth thereinto, and continuously withdrawing liberated sulfur froth from said eddies or whirlpools.

4. A method of treating sulfide ore concentrates or the like which comprises the steps of mixing the concentrates with water to form an easy owing pulp of substantially uniform density, agitating the pulp in a container in a circulatory path including a central downstream course and a surrounding cylindrical upstream course discharging into the downstream course in the top region of the body of pulp, and through a restricted area, introducing chlorine into the path whereby sulfur is liberated, breaking the iiow of pulp at the point of discharge to produce eddies or whirlpools at said point for transforming the sulfur into froth and for continuously collecting said froth thereinto, and continuously withdrawing liberated sulfur froth from said eddies or whirlpools.

References Cited in the ile of this patent UNTTED STATES PATENTS Number Name Date 412,300 Selwyn Oct. 8, 1889 748,461 Armbruster Dec. 29, 1903 843,986 Baker et al Feb. 12, 1907 1,049,746 Malm Jan. 7, 1913 1,111,788 Ewing Sept. 29, 1914 1,402,318 Rodebush Ian. 3, 1922 1,435,142 Angel Nov. 14, 1922 1,865,979 Tapie July 5, 1932 1,898,701 Westcott Feb. 21, 1933 1,904,583 Westcott Apr. 18, 1933 2,017,330 Traphagen Oct. 15, 1935 2,299,188 Stork et al Oct. 20, 1942 2,363,315 Grothe Nov. 21, 1944 FOREIGN PATENTS Number Country Date 23,493 Great Britain of 1900 

1. A METHOD OF TREATING SULFIDE ORE CONCENTRATES OR THE LIKE WHICH COMPRISES THE STEPS OF MIXING THE CONCENTRATES WITH WATER TO FORM AN EASY FLOWING PULP OF SUBSTANTIALLY UNIFORM DENSITY, AGITATING THE PULP IN A CONTAINER IN A CIRCULATORY PATH, INTRODUCING CHLORINE INTO THE PATH WHEREBY SULFUR IS LIBERATED, BREAKING THE FLOW OF THE PULP AT A POINT ALONG THE SURFACE THEREOF TO PRODUCE EDDIES OR WHIRLPOOLS ADAPTED FOR TRANSFORMING THE SULFUR INTO FROTH AND FOR CONTINUOUSLY COLLECTING SAID FROTH THEREINTO, AND CONTINUOUSLY WITHDRAWING SULFUR FROTH FROM SAID EDDIES OR WHIRLPOOLS. 